Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=false, destructiveHint=false, openWorldHint=true, and idempotentHint=false, so the safety profile is partly covered. The description adds meaningful behavioral context: credit-based OAuth pricing, a separate USD wallet for API keys, and a quote-then-confirm approval workflow. It still does not explain the output format or whether the original image is preserved.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three tight sentences: purpose first, then billing context, then the approval workflow. Every sentence is relevant and front-loaded, with no filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description covers the core operation, billing modes, and approval sequence, and the schema handles parameters fully. For a tool with no output schema, it could say more about the returned value (e.g., resulting image or job handle), but the essential invocation information is present.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the schema already documents all seven parameters, including the nested image object and the billing fields. The description adds only a workflow tie-in for quote/approval and does not add semantic meaning to prompt, mask_url, image_url, or image beyond what the schema provides. Baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The first sentence states a specific verb and resource ('Remove an object or person from a photo') and adds the gap-fill behavior, so the action is clear. It does not explicitly distinguish this tool from siblings like edit_image or remove_background, so it falls short of full sibling differentiation.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives procedural guidance for quote/approval and billing modes, which helps an agent decide how to invoke the tool. However, it never says when to choose erase_object over alternatives such as edit_image, remove_background, or remove_shadow, nor does it provide exclusions. Usage is implied by the purpose rather than explicitly routed.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.